[Android] $0 Lil Big Invasion: The Complete Adventure (Was $3.99) @ Google Play

Looks like a fun game. Rated 4.3 with over 10k installs and no IAP.

Those silly green guys got lost in tricky dungeons! As an aged firefly you have to find them, keep them together and lure them with your light to the exit - a giant vacuum cleaner - in order to suck them back home.

Use your index finger to outsmart winds, spider webs and glowing flowers. Find secret paths and meet helpful creatures. Activate switches, solve tricky puzzles and win epic boss fights with the power of your light. But be aware that flying consumes light energy. So keep your light recharged, rescue those silly guys and become a firefly hero!

Compete
Every dungeon in the main game has its own leaderboard. The quicker you get through the more points you will get. But be aware that the number of rescued guys counts as a multiplier. So make sure to catch them all when you go for that high score.